Final Project Journal

Project Overview:

This Arduino project is designed to automate environmental control based on humidity and temperature readings. It uses sensors to monitor these values and activates a pump, fan, and LED to maintain desired conditions, all controlled by a physical switch.

Code Breakdown:

1. Variable Declarations (Pin Assignments):
   
   

2. C++

const int pumpPin = 2;

const int fanPin = 3;

const int ledPin = 4;

const int humidityPin = A0;

const int temperaturePin = A1;

const int switchPin = 7;

3. 
   

   • const int: This keyword signifies that these integer variables are constants, meaning their values won't change during program execution.

   • Each line assigns a specific digital or analog pin number to a descriptive variable name. This makes the code more readable and maintainable.

   • For instance, pumpPin = 2 means the pump is connected to digital pin 2 of the Arduino.

   • A0 and A1 are analog pins.

4. Calibration Thresholds:
   
   

5. C++

const int humidityThreshold = 80;

const int temperatureHighThreshold = 27;

const int temperatureLowThreshold = 24;

6. 
   

   • These constants define the trigger points for the control logic.

   • humidityThreshold is the minimum percentage of humidity before the pump activates.

   • temperatureHighThreshold is the maximum temperature in degrees Celsius before the fan turns on.

   • temperatureLowThreshold is the minimum temperature in degrees Celsius before the LED turns on.

   • These values are adjustable to fine-tune the system's response.

7. setup() Function (Initialization):
   
   

8. C++

void setup() {

  Serial.begin(9600);

  pinMode(pumpPin, OUTPUT);

  pinMode(fanPin, OUTPUT);

  pinMode(ledPin, OUTPUT);

  pinMode(humidityPin, INPUT);

  pinMode(temperaturePin, INPUT);

  pinMode(switchPin, INPUT_PULLUP);

}

9. 
   

   • void setup(): This function runs once when the Arduino starts or resets.

   • Serial.begin(9600): Initializes serial communication at 9600 baud for debugging. This allows the Arduino to send data to a computer via USB.

   • pinMode(..., OUTPUT): Sets the pump, fan, and LED pins as outputs. This means the Arduino will send signals to these pins to control the connected devices.

   • pinMode(..., INPUT): Sets the humidity and temperature sensor pins as inputs. The Arduino will read analog values from these pins.

   • pinMode(switchPin, INPUT_PULLUP): Sets the switch pin as an input with an internal pull-up resistor. This simplifies the wiring by eliminating the need for an external resistor. When the switch is open, the pin will read HIGH. When closed, it will read LOW.

10. loop() Function (Main Program Loop):
    
    

11. C++

void loop() {

  int switchState = digitalRead(switchPin);

  if (switchState == HIGH) {

    // ... sensor readings and control logic ...

  } else {

    // ... turn off all devices ...

  }

  delay(1000);

}

12. 
    

    • void loop(): This function runs repeatedly after the setup() function.

    • int switchState = digitalRead(switchPin): Reads the state of the switch. If the switch is closed, switchState will be HIGH; otherwise, it will be LOW.

    • if (switchState == HIGH): This condition checks if the switch is closed. If it is, the code within the if block executes.

    • else: If the switch is open, the code within the else block executes, turning off all devices.

    • delay(1000): Pauses the program for 1 second (1000 milliseconds) before the next loop iteration. This prevents the Arduino from constantly checking the sensors and switch, reducing unnecessary processing.

13. Sensor Readings and Value Conversion (Inside if (switchState == HIGH)):
    
    

14. C++

int humidityValue = analogRead(humidityPin);

int temperatureValue = analogRead(temperaturePin);

float humidity = map(humidityValue, 0, 1023, 0, 100);

float temperature = map(temperatureValue, 0, 1023, -50, 100);

15. 
    

    • analogRead(humidityPin) and analogRead(temperaturePin): Read the analog values from the humidity and temperature sensors. These values range from 0 to 1023.

    • map(humidityValue, 0, 1023, 0, 100): Converts the analog humidity reading to a percentage (0-100).

    • map(temperatureValue, 0, 1023, -50, 100): Converts the analog temperature reading to degrees Celsius. Important: The -50 and 100 values should be adjusted based on the sensor's specifications.

16. Control Logic (Inside if (switchState == HIGH)):
    
    

17. C++

if (humidity < humidityThreshold) {

  digitalWrite(pumpPin, HIGH);

  Serial.println("Pump ON");

} else {

  digitalWrite(pumpPin, LOW);

  Serial.println("Pump OFF");

}

// Similar logic for fan and LED

18. 
    

    • These if-else statements implement the control logic.

    • If the humidity is below the humidityThreshold, the pump turns on (digitalWrite(pumpPin, HIGH)). Otherwise, it turns off (digitalWrite(pumpPin, LOW)).

    • Similar logic is used to control the fan based on temperatureHighThreshold and the LED based on temperatureLowThreshold.

    • Serial.println(...): Sends messages to the serial monitor indicating the status of each device.

19. Switch Off State (Inside else):
    
    

20. C++

else {

  digitalWrite(pumpPin, LOW);

  digitalWrite(fanPin, LOW);

  digitalWrite(ledPin, LOW);

  Serial.println("Switch OFF - all devices OFF");

}

21. 
    

    • If the switch is open (switchState == LOW), this code turns off all devices and prints a message to the serial monitor.

In essence:

The code continuously monitors the switch and, when it's closed, reads sensor data, converts it to meaningful units, and uses threshold values to control the pump, fan, and LED. When the switch is opened, all devices are turned off. This creates an automated environmental control system.